首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   842篇
  免费   102篇
儿科学   51篇
妇产科学   18篇
基础医学   143篇
口腔科学   72篇
临床医学   95篇
内科学   153篇
皮肤病学   27篇
神经病学   34篇
特种医学   7篇
外科学   59篇
综合类   12篇
预防医学   121篇
眼科学   19篇
药学   88篇
中国医学   1篇
肿瘤学   44篇
  2022年   5篇
  2021年   12篇
  2020年   13篇
  2019年   8篇
  2018年   6篇
  2017年   8篇
  2016年   7篇
  2015年   18篇
  2014年   25篇
  2013年   30篇
  2012年   45篇
  2011年   56篇
  2010年   31篇
  2009年   21篇
  2008年   44篇
  2007年   41篇
  2006年   50篇
  2005年   45篇
  2004年   43篇
  2003年   33篇
  2002年   22篇
  2001年   34篇
  2000年   26篇
  1999年   22篇
  1998年   13篇
  1996年   10篇
  1995年   8篇
  1994年   6篇
  1993年   5篇
  1992年   13篇
  1991年   15篇
  1990年   22篇
  1989年   21篇
  1988年   14篇
  1987年   12篇
  1986年   13篇
  1985年   15篇
  1984年   12篇
  1983年   8篇
  1981年   5篇
  1980年   5篇
  1979年   10篇
  1978年   5篇
  1973年   12篇
  1972年   5篇
  1971年   6篇
  1970年   7篇
  1969年   8篇
  1968年   7篇
  1944年   4篇
排序方式: 共有944条查询结果,搜索用时 40 毫秒
941.
X-linked lymphoproliferative disease (XLP1) is a rare immunodeficiency characterized by severe immune dysregulation and caused by mutations in the SH2D1A/SAP gene. Clinical manifestations are varied and include hemophagocytic lymphohistiocytosis (HLH), lymphoma and dysgammaglobulinemia, often triggered by Epstein-Barr virus infection. Historical data published before improved treatment regimens shows very poor outcome. We describe a large cohort of 91 genetically defined XLP1 patients collected from centers worldwide and report characteristics and outcome data for 43 patients receiving hematopoietic stem cell transplant (HSCT) and 48 untransplanted patients. The advent of better treatment strategies for HLH and malignancy has greatly reduced mortality for these patients, but HLH still remains the most severe feature of XLP1. Survival after allogeneic HSCT is 81.4% with good immune reconstitution in the large majority of patients and little evidence of posttransplant lymphoproliferative disease. However, survival falls to 50% in patients with HLH as a feature of disease. Untransplanted patients have an overall survival of 62.5% with the majority on immunoglobulin replacement therapy, but the outcome for those untransplanted after HLH is extremely poor (18.8%). HSCT should be undertaken in all patients with HLH, because outcome without transplant is extremely poor. The outcome of HSCT for other manifestations of XLP1 is very good, and if HSCT is not undertaken immediately, patients must be monitored closely for evidence of disease progression.  相似文献   
942.
Familial and epidemiological studies have shown that genetic factors play a role in the development and progression of type 2 diabetes mellitus (T2DM). Asian Indians have shown an increasing prevalence of T2DM. Apolipoprotein E (APOE) and Angiotensin-1 converting enzyme (ACE) I/D polymorphisms have been associated with T2DM. This study examined the association of APOE and ACE genes with T2DM patients of Punjab, India. APOE (HhaI) and ACE (I/D) genotypes analysed by polymerase chain reaction were available from 90 patients and 97 random healthy controls. All loci and populations are in Hardy-Weinberg equilibrium. There is no significant association of APOE vis-à-vis T2DM, however APOE*4 allele frequency is low in diabetics (3.9% and 8.8%). DD genotype and *D allele of ACE are associated with T2DM (OR=1.90, p<0.05, and OR=1.58, p<0.05, respectively). Recessive and multiplicative mode of inheritance for *D allele provided the strongest support for the association. Height, weight and BMI did not reveal any significant association with APO or ACE. DD-33 and ID-23 combinations (ACE-APOE) showed higher odds of 2.01 and 2.14, respectively. ACE but not APOE polymorphism is positively associated with T2DM in Indian population, however, the synergistic effects of DD-33 and ID-23 are also evident.  相似文献   
943.
The objectives of this study were to characterize rainbow trout (Oncorhynchus mykiss) corticotropin-releasing factor (CRF) and neuropeptide Y (NPY) cDNAs and to determine their mRNA levels in response to social stress. Standard cloning techniques were used to obtain cDNAs, sequences for trout NPY and two CRF isoforms. At the predicted amino acid level, our NPY sequence differs from the trout amino acid sequence reported by. A phylogenetic analysis suggests that the two CRF isoforms result from a gene duplication that occurred in a common ancestor of salmonids. A tissue distribution demonstrated that the mRNAs of both CRF isoforms are predominantly present in the preoptic area of the trout brain, whereas NPY mRNA is more abundant in the telencephalon. Pairs of sized-matched juvenile female trout were allowed to interact for 72 h and social ranks were assigned on the basis of behavioural observations. Mean plasma cortisol levels were 13-fold higher in subordinate than in dominant trout. As measured by ribonuclease protection assay, CRF1 and NPY mRNA levels were respectively 51 and 32% higher in the preoptic area of subordinate trout; in addition, CRF1 and NPY mRNA levels were positively correlated (R2=0.44). These results suggest that subordinate rainbow trout chronically maintain high levels of CRF mRNA during social stress and that NPY may be involved in the control of the stress axis in trout.  相似文献   
944.
PurposeThe mechanisms of the progression of Barrett’s oesophagus (BO) to oesophageal adenocarcinoma (OA) are poorly understood. The frequency of the 4977bp deletion in mitochondrial DNA (mtDNA) was investigated in specimens ranging from normal oesophageal tissue to OA in order to investigate whether this deletion represents a useful biomarker of disease progression.MethodsThe presence of the 4977bp deletion was screened by PCR amplification from 70 specimens in total.ResultsThe frequency of specimens with the 4977bp deletion increased in relation to the degree of dysplasia (8.3% in normal squamous epithelium; 15.4% in BO; 40% in low grade dysplasia (LGD); 69.2% in high-grade dysplasia and 90% in para-tumoural tissue). However, the frequency of the deletion reduced sharply in OA specimens (16.7%; p < 0.001).ConclusionThe mtDNA 4977bp deletion may be useful as a biomarker to detect the severity of dysplasia but not the presence of OA.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号